1. Field of the Invention
This invention relates to an electronic key system for a vehicle wherein radio communication is performed between a tranceiver (electronic key) carried by a user and a control apparatus mounted on an actual vehicle to verify an ID and, if a request received originates from a legal user, then starting of an engine or some other action is performed, and more particularly to an electronic key system for a vehicle suitable for use with, for example, a motorcycle.
2. Description of the Related Art
An electronic key system for a vehicle is disclosed, for example, in Japanese laid-open patent publication No. 2001-349110 and Japanese laid-open patent publication No. 2001-349117. In the electronic key system for a vehicle disclosed in Japanese laid-open patent publication No. 2001-349110 and Japanese laid-open patent publication No. 2001-349117, starting means (switches) are provided on a door handle and a trunk lid of an actual vehicle. If a user operates (starts) any of the starting means, then communication of a control apparatus with an electronic key is started. Then, the control apparatus verifies an ID transmitted thereto from the electronic key with an ID registered therein. Thus, if a result of the verifying that the IDs are coincident with each other is obtained, then door locking and so forth are released.
Further, in Japanese laid-open patent publication No. 2001-349110 and Japanese laid-open patent publication No. 2001-349117 described above, a starting means (switch) is provided also on an ignition knob. If the user operates the ignition knob after the user gets on the four-wheeled car, then the communication between the electronic key and the starting means is performed again to perform ID verifying for permitting starting of the engine. Then, if a result of the verifying that the IDs are coincident with each other, the engine is started.
In particular, in the conventional vehicle electronic key system for a four-wheeled car, the electronic key has a function for unlocking a door and a function for permitting starting of an engine.
Further, as a different prior art apparatus, an electronic key system is proposed (refer to, for example, Japanese laid-open patent publication No. 10-317754) wherein transmitting antennas are provided individually for doors of a four-wheeled car, and only that one of the doors which is approached by a portable device can be unlocked independently of the other doors of the vehicle.
In this manner, in the electronic key system described above, the range of transmitting from the control apparatus mounted on an actual vehicle in the communication between the control apparatus and the electronic key is small in comparison with that from the electronic key. Therefore, in the prior art apparatus described above, a plurality of transmitting antennas for outputting a signal from the control apparatus are provided depending upon different applications.
Incidentally, in order to apply such an electronic key system to a motorcycle, at least when a user gets on and operates the actual vehicle and when the user is running with the actual vehicle, it is necessary for the user to communicate with certainty with the electronic key carried by the user.
For example, depending upon the user, the electronic key is sometimes carried in a pocket of clothing or the like. In such an instance, if the communication of the control apparatus with the electronic key is interrupted, then there is the possibility that a locking mechanism for a handle bar installed on the actual vehicle cannot be placed into an unlocking state and the user may not be permitted to ride on and run with the actual vehicle.